Resting Metabolic Rate (RMR) Test
A resting metabolic rate (RMR) test measures the calories you burn at rest from your breath, not a calculator's guess. No needles, no radiation.
- Your real calories at rest. Formulas miss by more than 10% for 1 in 5 people
- Breathe normally through a mask for 10 to 20 minutes. No needles, no radiation
- No referral needed. Your report lands in your Mito dashboard, next to your labs
Why people order the Resting Metabolic Rate (RMR) Test
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Your weight loss has stalled
If you eat less and the scale won't move, the calorie number you're dieting against may be wrong for you. Measuring shows your real starting point instead of a formula's guess.
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Protect muscle on a GLP-1
On semaglutide or tirzepatide, resting burn tends to fall roughly in line with the lean mass you lose. Paired with a DEXA scan, RMR shows whether you're keeping muscle and how much to eat to protect it.
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Midlife and menopause
Body composition and the fuels you burn at rest change in midlife. Studies disagree on how much menopause itself lowers resting burn, so a measured number beats an assumption.
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Fuel your training
Heavy trainers need a real calorie floor to eat above. A measured RMR below 90% of predicted is one recognised sign of under-fueling in athletes.
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Wondering if your metabolism is slow
Resting burn, adjusted for muscle, holds steady from about 20 to 60. Most midlife change comes from losing muscle and moving less, and a test shows where you actually stand.
Not the right test if
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You want to check your thyroid
RMR isn't a thyroid test. Thyroid problems are diagnosed with a TSH and thyroid hormone blood test.
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You're pregnant or breastfeeding
Both change your resting burn, so the result won't reflect your usual baseline.
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You're ill right now
An infection can throw off the result. Book once you've recovered.
Why measure instead of using a calculator?
The best formula lands within 10% of measured for about 4 in 5 people without obesity and about 7 in 10 with obesity. Everyone else is off by more, often 150 calories a day or more, and a calculator can't tell you which group you're in. The Academy of Nutrition and Dietetics prefers a measured RMR over formulas when one is available.
Do I need a referral?
No. You order online. There's no physician's order or medical clearance for this test.
Does insurance cover it?
Usually not. Metabolic testing is elective, so plan to pay out of pocket.
Can I pay with my HSA or FSA?
Yes. You can pay with your HSA or FSA card at checkout.
How soon do I get results?
Reports usually arrive within 24 hours, and officially within 2 business days. They land in your Mito dashboard.
What members say on Trustpilot
What the Resting Metabolic Rate (RMR) Test measures
Your resting metabolic rate is the calories your body burns in a day just to stay alive: breathing, pumping blood, running your organs and keeping warm. For most people it is 60 to 75% of everything they burn in a day. It is the floor every calorie target is built on.
The test uses indirect calorimetry. While you rest, a metabolic cart measures the oxygen you breathe in and the carbon dioxide you breathe out. Burning calories always uses oxygen at a known rate, so your oxygen use converts directly into calories. The balance of the two gases also shows whether you're burning mostly fat or carbohydrate.
Online calculators guess your RMR from your sex, age, height and weight. They can't see how much muscle you carry, and about a quarter of the difference in resting burn between people isn't explained by body size, age or body composition at all. Two people with the same height and weight can burn very different amounts. This test measures yours.
- Report includes
- Measured RMR (calories per day), Predicted RMR and how yours compares, RER: fuel use at rest
- Method
- Indirect calorimetry: the oxygen you breathe in and the carbon dioxide you breathe out
- Equipment
- Metabolic cart with a face mask or clear hood
- Breathing time
- About 10 to 20 minutes, sitting or reclining
- Visit length
- 30 to 60 minutes
- Needles or radiation
- None
- Results
- On your Mito dashboard
Calculator, smartwatch or measured RMR?
| Compare | Online calculator | Smartwatch | Measured RMR test |
|---|---|---|---|
| How it gets your number | A formula using sex, age, height and weight | An estimate from your profile, with movement and heart rate added for activity | Measures the oxygen you use and carbon dioxide you breathe out |
| Sees your muscle | No | No | Yes, its effect on your burn shows up in the measurement |
| How close it gets | Best formula within 10% for about 4 in 5 people without obesity, 7 in 10 with obesity | Varies by device, and the resting part is still an estimate | Repeat tests usually agree within 2 to 4% |
| Shows fuel use | No | No | Yes, fat versus carbohydrate at rest |
| Best for | A rough starting point | Day-to-day activity trends | A personal calorie floor you can plan around |
Your results
What your Resting Metabolic Rate (RMR) Test report shows
There's no single normal RMR. It depends on your size and, most of all, your muscle, which is why your number sits next to a prediction for someone like you.
Measured RMR (calories per day)
The calories your body burns in 24 hours at complete rest, measured from your breath. Add activity and digestion on top to get your total daily needs.
Predicted RMR and how yours compares
The number a standard prediction equation expects for someone of your sex, age and size. If you measure 1,200 and the prediction is 1,400, you burn about 14% less at rest than calculators assume, roughly 200 calories a day.
RER: fuel use at rest
The ratio of carbon dioxide out to oxygen in. About 0.7 means mostly fat, about 0.85 a mix, and about 1.0 mostly carbohydrate. At rest it reflects your recent meals, not a fixed "fat burner" type.
Measured compared with predicted
Divide your measured RMR by your predicted RMR. This is context for planning, not a diagnosis.
| Measured vs predicted | What it usually means |
|---|---|
| Below 90% | You burn less at rest than a formula expects for your size. Common after dieting or losing muscle. In athletes it is one sign of under-fueling. Worth discussing, and a reason to check labs, not a diagnosis. |
| 90 to 110% | Your resting burn is in line with the formula. Calculators are a fair guide for you. |
| Above 110% | You burn more at rest than formulas assume, so a calculator would set your calories too low. |
The 10% margin is the accuracy cutoff used in a systematic review of RMR prediction equations (Frankenfield and colleagues, 2005). A measured to predicted ratio below 0.90 is listed as an indicator of low energy availability in the 2023 International Olympic Committee consensus statement on Relative Energy Deficiency in Sport.
What this test can't tell you
- It's one morning's snapshot. Sleep, stress, illness and your menstrual cycle can shift it, so retest under the same conditions. A change needs to be more than about 6 to 8% to be real.
- It isn't a thyroid test or a diagnosis of any condition. Thyroid function is checked with a TSH blood test.
- Your resting fuel use reflects your recent meals and the fast, not a fixed metabolic type.
- It covers rest only. Calories burned through activity and digestion are still estimates.
How it works
What to expect from your Resting Metabolic Rate (RMR) Test
- 1 Order online
Check out on Mito. No referral or medical clearance needed.
- 2 Book a morning slot
Choose a partner center and your preferred times. You get a confirmation, usually within hours. A morning time means most of the 12-hour fast happens while you sleep, and you have breakfast and coffee straight after.
- 3 Arrive calm
Nothing but water beforehand, no workout the day before, and an easy trip in. Food, caffeine and exertion raise your burn for hours, which would inflate your number.
- 4 Breathe normally
Sit or recline and breathe through a mask or hood for about 10 to 20 minutes. No needles, no radiation, nothing to do but relax. The whole visit takes 30 to 60 minutes.
- 5 Get your report
Results usually arrive within 24 hours and land in your Mito dashboard, next to your labs. Retest after a meaningful change in weight, under the same conditions.
Every result comes with a plan
Your test report arrives in your Mito dashboard alongside your lab results, and your membership plan uses it.
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Your report in your dashboard. Your test results arrive in your Mito dashboard, next to your lab results.
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Part of your plan. With membership, your personalized action plan takes your test results into account.
Resting Metabolic Rate (RMR) testing you can trust
Handled under HIPAA
- Order online, then book at a partner center
- Your data is encrypted, handled under HIPAA, and never sold
Overseen by our Care Team Lead
Every result, including your Mito Brain analysis, is checked by Rhonda Collins, FNP-C, our Care Team Lead and a board-certified Family Nurse Practitioner with over 15 years of nursing experience across cardiac ICU, primary care, and dermatology.
Meet RhondaCommon Resting Metabolic Rate (RMR) Test questions
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How do availability and prices vary by state?
Available in all 50 states and Washington, DC.
| States | Provider | Availability | Member price | Non-member price |
|---|---|---|---|---|
| All 50 states and DC | Fitnescity Health | Available | $140.40 | $196.56 |